Web Filters More Effective at Blocking Health Info Than Pornography

Daniel J DeNoon

December 10, 2002

Dec. 10, 2002 — All Web filtering software mistakenly blocks access to medical information, according to a study in the Dec. 11 issue of The Journal of the American Medical Association. Some experts say that parents should be advised not to use the Web filters, but to obtain reliable information about how to use the Internet so that their children will be protected.

Although Web filters all have several settings, at their least restrictive settings, they block 87% of pornography and 1.4% of general health information in typical health-related searches. Also, at this least restrictive setting they block 10% of health sites with information about sexually transmitted diseases, safe sex, condom use, and homosexuality. At the more-often-used, more restrictive settings, the filters block only slightly more pornography but they block up to 17 times more health information.

This is a particular problem for teenagers who need sex-related health information, says study leader Caroline R. Richardson, MD. Richardson, a professor of family medicine at the University of Michigan Medical School and a family services investigator for the Veterans Affairs Health Services.

"Up to 60% of sexually related health information is blocked," study leader Caroline R. Richardson, MD, told Medscape. "Teens don't have heart attacks very often. They don't often get cancer. What do they have problems with? It relates to sexuality. We have data that many of these teens are looking up information on sexually transmitted diseases, safe sex, and homosexuality. These are the most common types of questions that they turn to the Internet for."

When the researchers searched for pornography instead of health information, the filters were far less effective in blocking access to objectionable Web sites.

Dr. Richardson and colleagues conclude that at the least restrictive settings, filtering software does an adequate job of blocking pornography while providing access to health information. But they warn that more restrictive settings don't block much more porn but seriously block other information.

That's the wrong conclusion, says Geoffrey Nunberg, PhD, a Stanford University professor of linguistics and an expert in automatic classification of information. Nunberg was an expert witness for the American Library Association (ALA) lawsuit protesting a law requiring libraries to install Web filters on computers used by minors. A circuit court struck down the part of the law pertaining to libraries but left intact the portion of the law requiring Web filters for schools. The Supreme Court is scheduled to consider the issue on Feb. 14, 2003.

"To say that at the least restrictive settings the filters don't substantially impede access while they do impede porn is misleading," Dr. Nunberg told Medscape. "If you close 87% of pornographic bookstores in your community you don't really restrict access, just variety. Teenagers who are looking for this stuff tend to be very persistent, so this figure is not very reassuring."

The real question, Dr. Nunberg says, isn't whether teens looking for pornography can find it. The issue is whether important information gets censored. He argues that even if some information is available elsewhere, important information may be blocked.

"Several of the filters block the excellent teen information on the Planned Parenthood site," Dr. Nunberg says. "My teen daughter isn't going to come to me for this kind of information, so I'd like her to go there. But she may not be able to get it. And Planned Parenthood is an important site; an important brand teens may look for. So to say they can get it elsewhere isn't true."

The makers of Web filtering software argue that it works better than most people think. David Burt is public relations manager for N2H2, the Web filtering software used by about 40% of schools. He said software settings make it easy to adjust how much information gets blocked. When blocking mistakes happen, he added, it's easy to fix them.

"If a person finds a Web site is blocked by a filter, that is an inconvenience but there are ways built into the software to deal with that," Mr. Burt told Medscape. "The system administrator can override the software to let the person get access. If a person is too embarrassed to ask, he or she can submit an anonymous request to have the site reviewed.

But Emily Sheketoff, ALA executive director, says the study shows filters just don't work.

"Even at their highest settings, filters fail to block porn sites when users did health searches," Ms. Sheketoff told Medscape. "If a parent is depending on a filter, 13% of the time they will be exposed to pornography. At the same time, important information on safe sex, condoms, and gay health issues will be blocked 10% of time. We are pleading with parents and teachers not to use filters, but to get good information on how to use the Internet so children can be protected and still have a safe and rewarding experience."

JAMA. 2002;288:2887-2894

Reviewed by Gary D. Vogin, MD


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